The solitary rectal ulcer syndrome is an uncommon entity consisting of a rectal abnormality caused by straining during defecation and characterized by specific histologic changes. Endoscopy may show single or multiple ulcers or a preulcerative phase consisting of mucosal thickening. Findings on barium enema may be normal or nonspecific, consisting of a thickened valve of Houston, nodularity, and rectal stricture. Pathologic changes consist of replacement of the lamina propria by fibroblasts and smooth muscle fibers with marked hypertrophy of the muscularis mucosae. In five patients with histologically proved solitary rectal ulcer syndrome, defecography was performed to evaluate the accompanying defecation disorder. Two patients showed the spastic pelvic floor syndrome, characterized by failure of relaxation of the pelvic floor musculature during straining. In the remaining three, defecography showed an infolding of the rectal wall toward the rectal lumen increasing gradually to form an intussusception. The results indicate that defecography is useful to show the underlying disorder of defecation in the solitary rectal ulcer syndrome.